United plans to resume 787 service in May

A 787 Dreamliner passenger jet is tested above the Boeing factory at Paine Field in Everett, Washington state on March 20, 2011.

Story highlights

United Airlines is only U.S. carrier that flies the 787; 50 in service worldwide

The 787 was grounded in January after two battery fires in Boston and Japan

The Federal Aviation Administration must still sign off on Boeing's battery redesign

United Airlines plans to resume flying the 787 Dreamliner in May, the carrier told CNN in anticipation of regulatory approval of Boeing's remedy for battery problems that forced the jetliner's worldwide grounding.

While United is the only U.S. carrier that flies the wide body, a signal from the world's biggest carrier indicates that others are also likely making plans to resume service in coming weeks.

For the first time in months, it also indicates a clear time line for Boeing to return the aggressively promoted but troubled jetliner to the skies after it was grounded by regulatory authorities globally in January.

"We are in the process of formulating our domestic flying plans and will be making additional schedule changes as we gain visibility to the time line for certification and modification work," Christen David, an airline spokeswoman said.